My friend David Weinberger, an author and deep thinker, once updated the famous Andy Warhol line for the era of the blog. Weinberger said, "In the future, everyone will be famous for 15 people."

Fame is double-edged, of course. So an addendum: In the future, everyone will face public vilification.

The rise of online conversation has given us wonderful new ways to tell one another what we know. It's also given people a forum with which to tear other people a proverbial new you-know-what.

Sometimes the approbation is at least understandable, even when it goes overboard. In South Korea, a young woman's indifference to her pet's, ahem, messy behavior aboard public transportation earned her a torrent of online abuse, to the point that her life was severely affected.

Some people have been unfairly targeted by online mobs, meanwhile. And so have some companies.

Corporate executives know they can't please everyone all the time. But what happens when someone creates an especially compelling online rant that is downright unfair? The answer is: Get over it, but deal with it, too.

PR people know this all too well. Even a fine product can get an unfine reputation resulting from rumors, poor reporting, or other factors a company can't immediately counter. Conversely, clever marketing has worked wonders with lousy products. The Internet is changing the equation, slowly.

Like many other buyers of products, I now go online to see what people say about them. But the last thing I'd do is assume any individual tale is true. If I see a blizzard of similar stories, a litany of woes about a particular product or service, I have to at least ask myself whether amid all that smoke may be some flame.

What I'm getting at is the duty of the reader in a world of media-everywhere. We'll all have to learn a modern version of old-fashioned media literacy.

I realize "media literacy" is a snore-inducing term. But it's more vital than ever. And it's not just about consumption anymore. It's also about production, though I don't think the act of posting a video on YouTube makes someone fully media-literate. Yes, it helps them understand how to create video, but they also need to understand how media are used to sell and persuade.

And when anyone can say anything about anyone (or anything) in a public forum, we must revisit the first rule that journalists learn: Be skeptical. That's especially vital when the speaker is anonymous or using a pseudonym; anyone who doesn't stand behind his or her own words does not deserve immediate trust.

I hope people will learn not to immediately believe anything they read, hear, or see in whatever medium - positive or negative - unless it's from a source they have come to trust. A dollop of skepticism will go far.

This means something more: Trust will be harder than ever to earn. But once it is, it'll probably also have more staying power.

Dan Gillmor is the author of We the Media: Grassroots Journalism By the People, For the People. His blog is at bayosphere.com/blog/dangillmor. He is also director of the Center for Citizen Media.